Discrete cofired feedthrough filter for medical implanted devices

ABSTRACT

Discrete cofired feedthrough filters are provided for medical implanted device applications. A plurality of discrete vertical feedthrough filter elements are respectively associated with a plurality of signal wires or pins otherwise supported by an insulating feedthrough and a ferrule. The resulting discrete device comprises a single-element device which is cheaper to make, and which reduces cross-talk between adjacent signal wires/pins while otherwise accommodating changes in feedthrough pitch without having to redesign the filter.

PRIORITY CLAIM

This application claims the benefit of previously filed U.S. ProvisionalPatent Application entitled “DISCRETE COFIRED FEEDTHROUGH FILTER FORMEDICAL IMPLANTED DEVICES,” assigned U.S. Ser. No. 62/169,201, filedJun. 1, 2015, and which is incorporated herein by reference for allpurposes.

FIELD OF THE SUBJECT MATTER

The presently disclosed technology relates to feedthrough filters andcorresponding methodologies. More particularly, the presently disclosedtechnology relates to manufacturing and use of discrete cofiredfeedthrough filters for use with active implantable medical devices(AIMD).

BACKGROUND OF THE SUBJECT MATTER

Heart pacemakers and other implantable medical devices includeelectronic components contained within an outer housing. The outerhousing of the implantable medical device can be formed of anappropriate material to withstand implantation within a human body.Implantable electronics can be shielded from external sources ofelectromagnetic interference (EMI) using a filter.

Conventionally, a feedthrough filter can be coupled to an implantablemedical device such that feed wires of the device pass through thefeedthrough filter as close as practical to the to the input-outputconnector on the implanted device. For example, as illustrated in FIGS.38 and 39 of commonly owned United States Patent Application PublicationNo. 20140062618, a conventional implantable system 10 can include acanister or ferrule 11 through which feed wires 12 pass in order toconnect between external circuitry of an implanted device and internalcircuitry of the implanted device. The canister 11 can include a bushing13 to secure and protect the feed wires 12. Bonding material 14 can beused to secure the feed wires 12 in the canister 11.

Further per such Publication No. 20140062618, a feedthrough filter 15can be disposed within the canister 11. Feed wires 12 completely passthrough feedthrough filter 15 to connect between the internal andexternal circuitry of the implanted device. The feedthrough filter 15can act as a capacitor such that the each of the feed wires 12 of thedevice is electrically connected to a respective set of electrode plates16 and 17 within the feedthrough filter by the electrically conductivevia 18. Conductive plates 17 are interleaved between conductive plates16 to produce the capacitance effect. However, such feedthrough filtersoften require numerous intricate manufacturing steps and are susceptibleto damage during manufacture and assembly prior to implantation. Thecomplete disclosure of such Publication No. 20140062618 is fullyincorporated herein by reference and for all purposes.

Thus, a need exists for an improved electromagnetic interference filterfor implantable medical devices. More particularly, it would bedesirable to have a filter that can reduce manufacturing cost while alsoimproving installed characteristics. While various implementations ofelectromagnetic interference filters for implantable medical deviceshave been developed, no design has emerged that generally encompassesall of the desired characteristics as hereafter presented in accordancewith the subject technology.

SUMMARY OF THE SUBJECT MATTER

The presently disclosed subject matter recognizes and addresses variousof the foregoing issues, and others concerning certain aspects offiltering devices. Thus, broadly speaking, an object of certainembodiments of the presently disclosed technology is to provide improveddesigns for certain components and component assemblies associated withfiltering devices, and more particularly to provide improvedelectromagnetic interference filters for implantable medical devices.Other objects, broadly speaking relate to providing discrete cofiredfeedthrough filters for implanted medical devices and relatedmethodologies.

Aspects and advantages of the presently disclosed subject matter will beset forth in part in the following description, or may be apparent fromthe description, or may be learned through practice of the presentlydisclosed subject matter, which relates in some presently disclosedembodiments to an improved electromagnetic interference filter forvarious electronic devices such as implantable medical devices.

Other present objects relate to construction and surface mounting ofdiscrete filter devices on substrates such as directly on insulatedfeedthrough arrangements or on other supporting substrates such asprinted circuit boards (PCB's) so as to provide both mechanical andelectrical connection.

Aspects of other exemplary embodiments of the presently disclosedsubject matter provide improved electrical and mechanical coupling ofcertain mounted devices to circuits or traces on a printed circuit boardon which an associated device may be mounted.

Still further aspects of yet still other embodiments of the presentlydisclosed subject matter provide enhancements to manufacturing and/ormounting methodologies associated with the use of discrete, direct mounttype devices.

One exemplary embodiment of presently disclosed subject matter relatesto a feedthrough filter arrangement for use with an active implantablemedical device (AIMD), comprising a ferrule; a feedthrough associatedwith such ferrule; a plurality of conductors supported through suchfeedthrough; and a corresponding plurality of discrete filters.Preferably, each of such filters has at least two respective terminals,with one of such terminals associated with a respective one of suchconductors, and the other of such terminals associated with suchferrule.

In some instances thereof, such conductors may comprise respective wireconductors for each of such discrete filters. In others, such ferrulemay comprise a metal ferrule; and such feedthrough may comprise aninsulating cofired feedthrough which is mounted relative to such metalferrule.

In another exemplary variation of the foregoing exemplary feedthroughfilter arrangement, each of such filters may have side and endterminals, and may have two sets of interleaved vertical electrodescomprising ground electrodes and signal electrodes; each of such groundelectrodes may have respective projecting end portions connecting withrespective end terminals of each of such filters; and each of suchsignal electrodes may have respective projecting side portionsconnecting with respective side terminals of each of such filters.

In another variation thereof, such at least two respective terminals maycomprise side and end terminals associated respectively with suchfilters and such ferrule; and each of such filters may have two sets ofinterleaved vertical electrodes comprising ground electrodes and signalelectrodes. Per such variation, preferably such ground electrodes areassociated with at least one end terminal of each respective filter sothat ground is connected to such ferrule, and such signal electrodes areassociated with at least one side terminal of each respective filter sothat signals on a respective associated conductor are connected to suchassociated conductor. In some variations thereof, such respective sideand end terminals may comprise asymmetrical terminals. For some ofthose, such feedthrough may include a double row of conductors supportedtherethrough, and such filters may be mounted on such feedthrough in arow with end terminals thereof on alternate sides of such feedthrough.

In another alternative of such exemplary foregoing feedthrough filterarrangement, side terminals of such filters may comprise respective topand bottom side terminals, with each bottom side terminal respectivelyconnected to the associated conductor of its filter, and with each topside terminal connected to an associated AIMD.

In other alternatives thereof, such respective side and end terminalsmay include at least a pair of end terminals for each respective filter,and may comprise symmetrical terminals for each respective filter. Persome of such exemplary alternatives, such ferrule may comprise atitanium ferrule with sets of upper surface gold pads attached to groundof such ferrule; and such filters may be mounted relative to suchferrule such that such end terminals for each respective filter areattached to a set of such gold pads of such ferrule. Per others thereof,such conductors may be supported in a single row in such feedthrough,and respective end terminals of each of such filters may be mounted onopposite sides of such feedthrough, with a bottom side terminal of eachof such elements situated over respective of such conductors.

For other presently disclosed variations, at least some of such filtersmay further include additional ground electrodes for relatively lowerdcR filter characteristics. Still further, at least some of such filtersmay further include additional signal electrodes for relatively lowerESR filter characteristics. In some such variations, at least some ofsuch filters further include additional ground electrodes for relativelylower dcR filter characteristics; and additional signal electrodes forrelatively lower ESR filter characteristics; and some of such electrodesmay comprise relatively lower resistance metals.

In some presently disclosed alternatives, such filters may includerelatively low dielectric materials made from NPO dielectric materials.For others, such filters may further include a plurality of dummyelectrode layers providing nucleation areas for plating formation offilter terminals. In some such variations, such ground and signalelectrodes and such dummy electrode layers may include additionalshielding members for relatively increasing the dielectric withstandingvoltage characteristics of such filters.

Another exemplary embodiment of presently disclosed subject matterrelates to a feedthrough filter arrangement for use in association withexternal circuitry. Such arrangement preferably comprises a metalferrule; an insulating feedthrough associated with such ferrule; aplurality of wire conductors supported through such feedthrough; and acorresponding plurality of discrete cofired filter capacitors. Each ofsuch filter capacitors preferably have respective end terminals; a topside terminal; a bottom side terminal; a body of dielectric material;and two sets of interleaved vertical electrodes comprising groundelectrodes and signal electrodes received in such body of dielectricmaterial. Further, each of such ground electrodes preferably hasrespective projecting end portions connecting with respective endterminals of each of such filter capacitors, and each of such signalelectrodes preferably has respective projecting side portions connectingwith respective side terminals of each of such filter capacitors. Also,respective end terminals of each of such filter capacitors arepreferably mounted on opposite sides of such ferrule for a groundconnection therewith, and with a bottom side terminal of each of suchfilter capacitors connected with a respective one of such conductors fora signal connection therewith, so that each of such top side terminalsof such filter capacitors are exposed for respective connections withassociated external circuitry.

For some such exemplary feedthrough filter arrangements, at least someof such filter capacitors may further include additional groundelectrodes for relatively lower dcR filter capacitor characteristics;and additional signal electrodes for relatively lower ESR filtercapacitor characteristics. In still other variations thereof, suchferrule may comprise a titanium ferrule with sets of upper surface goldpads attached to ground of such ferrule; and such filter capacitors maybe mounted relative to such ferrule such that such end terminals foreach respective filter are attached to a set of such gold pads of suchferrule. For some, at least some of such filter capacitors may furtherinclude a plurality of dummy electrode layers providing nucleation areasfor plating formation of filter capacitor terminals. For other presentlydisclosed variations, such ground and signal electrodes and such dummyelectrode layers may include additional shielding members for relativelyincreasing the dielectric withstanding voltage characteristics of suchfilter capacitors.

Still further, it is to be understood that the presently disclosedtechnology equally applies to the resulting devices and structuresdisclosed and/or discussed herewith, as well as the correspondinginvolved methodologies.

One presently disclosed exemplary methodology for a feedthrough filterarrangement for use with an active implanted medical device (AIMD) maypreferably comprise providing a metal ferrule; fitting an insulatingfeedthrough with such ferrule; supporting a plurality of conductorsthrough such feedthrough; and connecting respectively a correspondingplurality of discrete cofired filters with such plurality of conductors,so as to reduce cross-talk between signals on adjacent of suchconductors.

Some variations of such presently disclosed methodology may furtherinclude providing a double row of conductors supported through suchfeedthrough; and providing each of such filters with at least one endterminal and at least one side terminal; and mounting such filters onsuch feedthrough in a row with end terminals thereof on alternate sidesof such feedthrough. Other alternatives may further include connectingand directly mounting such plurality of discrete cofired filters with aprinted circuit board instead of connecting with such plurality offerrule conductors.

Yet other variations may further include providing each of such filterswith at least two respective terminals, with one of such terminalsassociated with a respective one of such conductors, and the other ofsuch terminals associated with such ferrule. In some such variations,methodology may further include providing such filter terminals aseither symmetrical or asymmetrical terminals.

In still other variations of presently disclosed methodology, such atleast two respective terminals may comprise side and end terminalsassociated respectively with such filters and such ferrule; and each ofsuch filters may have two sets of interleaved vertical electrodescomprising ground electrodes and signal electrodes, so that such groundelectrodes are associated with at least one end terminal of eachrespective filter so that ground is connected to such ferrule, and sothat such signal electrodes are associated with at least one sideterminal of each respective filter so that signals on a respectiveassociated conductor are connected to such associated conductor. Inother alternatives, side terminals of such filters may compriserespective top and bottom side terminals, with each bottom side terminalrespectively connected to the associated conductor of its filter, andwith each top side terminal connected to an associated AIMD.

Per other variations, each of such filters may comprise filtercapacitors having respective end terminals, a top side terminal, abottom side terminal, a body of dielectric material; and two sets ofinterleaved vertical electrodes comprising ground electrodes and signalelectrodes received in such body of dielectric material. In suchinstances, preferably each of such ground electrodes have respectiveprojecting end portions connecting with respective end terminals of eachof such filter capacitors, and each of such signal electrodes haverespective projecting side portions connecting with respective sideterminals of each of such filter capacitors.

In other presently disclosed alternatives, methodology may furtherinclude selectively providing additional electrodes to such filtercapacitors for relatively lower dcR and/or relatively lower ESR filtercharacteristics. Still other variations may further include selectivelyproviding a plurality of dummy electrode layers to such filtercapacitors for providing nucleation areas for plating formation offilter capacitor terminals. Other variations may further includeselectively providing additional shielding members to selected of suchground and signal electrodes and such dummy electrode layers forrelatively increasing the dielectric withstanding voltagecharacteristics of such filter capacitors.

For yet other presently disclosed alternatives, respective end terminalsof each of such filter capacitors may be mounted on opposite sides ofsuch ferrule for a ground connection therewith, and with a bottom sideterminal of each of such filter capacitors connected with a respectiveone of such conductors for a signal connection therewith, so that eachof such top side terminals of such filter capacitors are exposed forrespective connections with associated external circuitry.

For others, mounting of such end terminals of such filter capacitors onsuch ferrule may include using surface tension of solder forself-alignment of such capacitors during a solder reflow step, whichcauses auto-rotation and centering of the capacitor whenever the solderis heated up for reflow. For some of such variations, presentlydisclosed methodology may further include attaching a lead to suchcapacitor after such reflow step, to secure the positioning of suchcapacitor relative to such ferrule.

Yet further aspects of still other embodiments of the presentlydisclosed subject matter provide features for improved low seriesresistance, or improved high breakdown voltage characteristics, orimproved lower costs for assembly, or for satisfying needs for specialtyconfigurations.

Additional aspects of the presently disclosed subject matter relate toimprovements in single element 3- or 4-terminal feedthrough filters formedical implantable devices. As a single element device, the presentlydisclosed subject matter is less expensive to manufacture thanconventional filters which are constructed as arrays of elements in asingle device, with holes for signal wires. Also, the presentlydisclosed subject matter is advantageous to help reduce cross-talkbetween adjacent or nearby wires, and can accommodate changes infeedthrough pitch without having to redesign the filter.

Other presently disclosed aspects of improved discrete cofired filterdevices are achieved through various combinations of vertically orientedelectrodes, paired electrodes, shielded electrodes, and asymmetricterminals. Other presently disclosed aspects of improved discretecofired filter devices are achieved through various combinations withFCT (fine copper termination) technology. See, for example, commonlyowned U.S. Pat. No. 6,960,366 and its related patents, the disclosuresof all of which are fully incorporated herein by reference and for allpurposes.

Still other aspects of presently disclosed technology are resulting ESL(equivalent series inductance) similar as a conventional FT(feedthrough) array, while having low ESR and dcR in an easily mounteddiscrete device. Manufacturing costs are low, and shielded structureembodiments have substantially higher working voltage than correspondingnon-shielded parts.

Still further, per certain aspects of presently disclosed technology,elimination of top wrap from ground terminal reduces tendency forsurface arcing.

Yet further, while the presently disclosed technology is intended foroperation in conjunction with an implanted medical feedthrough, it willproved other uses for feedthroughs such as when an associated signal isrouted from top to bottom surfaces. For instance, decoupling of highpower transistors is one such additional use.

Other presently disclosed embodiments relate to advantageous increasesof dielectric withstand voltage (DWV) characteristics through the use ofcertain presently disclosed shielding features.

It is a further general object to provide relatively low manufacturingcosts combined with relatively improved characteristics for discretecofired feedthrough filter devices.

Additional objects and advantages of the presently disclosed subjectmatter are set forth in, or will be apparent to those of ordinary skillin the art from, the detailed description herein. Also, it should befurther appreciated by those of ordinary skill in the art thatmodifications and variations to the specifically illustrated,referenced, and discussed features and/or steps hereof may be practicedin various embodiments and uses of the disclosed technology withoutdeparting from the spirit and scope thereof, by virtue of presentreference thereto. Such variations may include, but are not limited to,substitution of equivalent means, steps, features, or materials forthose shown, referenced, or discussed, and the functional, operational,or positional reversal of various parts, features, steps, or the like.

Still further, it is to be understood that different embodiments, aswell as different presently preferred embodiments, of this technologymay include various combinations or configurations of presentlydisclosed steps, features or elements, or their equivalents (includingcombinations of features, configurations, or steps thereof not expresslyshown in the figures or stated in the detailed description).

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling description of the presently disclosed subjectmatter, including the best mode thereof, directed to one of ordinaryskill in the art, is set forth in the specification, which makesreference to the appended figures, in which:

FIG. 1A illustrates a generally sides and top perspective view of anexemplary embodiment in accordance with the presently disclosedtechnology;

FIGS. 1B and 1C respectively illustrate cross-sectional representationsof the ground electrode and signal electrode internal geometry of theexemplary embodiment of present FIG. 1A;

FIG. 2 represents electromagnetic flow lines of a prior art discoidalfeedthrough filter, the electrical structure of which is mimicked by thepresently disclosed exemplary embodiment of present FIG. 1A;

FIGS. 3A and 3B are respective side and top views illustratingconceptual layouts of filter conductors, positioned relative to arepresentative metal ferrule and insulating feedthrough;

FIGS. 4A and 4B illustrate exemplary symmetric and asymmetric terminalarrangements as may be practiced with the presently disclosed subjectmatter;

FIGS. 5A, 5B, and 5C illustrate respective approaches to lowering seriesresistance which may be practiced in conjunction with the presentlydisclosed subject matter, particularly representing standard design, LowdcR design and Low dcR/ESR design, respectively;

FIG. 6A is an exemplary embodiment of presently disclosed subjectmatter, similar to the illustrations of present application FIGS. 1A and4A, and intended to be mounted on a ferrule and feedthrough as two ofsuch embodiments (of FIG. 6A) are represented in mounted configurationby the perspective illustration of present FIG. 6B;

FIGS. 7A and 7B represent, respectively, side and end views of thesignal layer internal structures of the exemplary embodiment of presentFIG. 6A;

FIG. 7C represents the ground layer internal structures (side view) ofthe exemplary embodiment of present FIG. 6A;

FIG. 7D illustrates an alternate ground pattern (alternative to FIG. 7C)which results with an asymmetric terminal (with no wrapping on the topsurface);

FIGS. 8A and 8B illustrate, respectively, end and top views (in partialsee-through illustration) of a discrete vertical feedthrough filter ofpresently disclosed subject matter in combination with a supportingferrule, insulating feedthrough, and terminal wire, similar to theperspective view combination of subject FIG. 6B;

FIG. 8C illustrates an enlarged top view in isolation of the presentlydisclosed discrete vertical FT filter show in combination illustratedwith subject FIGS. 8A and 8B;

The two respective illustrations of subject FIG. 8D show top views ofrepresentative A and B patterns for signal pins of the illustratedexemplary embodiment of present FIG. 8A;

The illustration of subject FIG. 8E shows a top view of a representativepattern for RF pins as may be associated with the illustrated exemplaryembodiment of present FIG. 8A;

The illustration of subject FIG. 8F shows a top view of a representativepattern for ground pins as may be associated with the illustratedexemplary embodiment of present FIG. 8A;

The representative preliminary electrode layer designs represented bypresent FIGS. 9A, 9B, and 9C, illustrate respectively top views ofsignal, ground, and dummy electrode layers of such design;

Respective FIGS. 10A, 10B, and 10C respectively illustrate signal,ground, and dummy electrode layers as presently disclosed for a shieldeddesign for increasing DWV (dielectric withstand voltage); and

FIGS. 11A and 11B represent exemplary alternative device configurations,with FIG. 11A representing a top view of a double-ended filter inassociation with a single row feedthrough, and FIG. 11B representing atop view of a single-ended filter in association with a double rowfeedthrough.

Repeat use of reference characters throughout the present specificationand appended drawings is intended to represent same or analogousfeatures, elements, or steps of the presently disclosed subject matter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed in the Summary of the Subject Matter section, the presentlydisclosed subject matter is generally concerned with improvedfeedthrough filter devices and related technology and manufacturingand/or mounting methodology thereof. More particularly, the presentlydisclosed subject matter is concerned with improved designs for certaindiscrete vertical feedthrough filters and related methodologies.

Selected combinations of aspects of the disclosed technology correspondto a plurality of different embodiments of the presently disclosedsubject matter. It should be noted that each of the exemplaryembodiments presented and discussed herein should not insinuatelimitations of the presently disclosed subject matter. Features or stepsillustrated or described as part of one embodiment may be used incombination with aspects of another embodiment to yield yet furtherembodiments. In additional, certain features may be interchanged withsimilar devices or features not expressly mentioned which perform thesame or similar function.

Reference will now be made in detail to exemplary presently preferredembodiments, and for which FIG. 1A illustrates a generally sides (oneside and one end) and top perspective view of an exemplary embodiment ofa filter capacitor 20 in accordance with the presently disclosedtechnology, while FIGS. 1B and 1C respectively illustratecross-sectional representations of the ground electrode 22 and signalelectrode 24 internal geometry of the exemplary embodiment of presentFIG. 1A. As understood by those of ordinary skill in the art from thecomplete disclosure herewith and accompanying illustrations, suchelectrodes 22 and 24 are received within dielectric material 26 formingthe main body of filter capacitor 20. Such discrete vertical electrodefilter arrangement mimics the electrical structure of a prior artdiscoidal feedthrough filter generally 28, as represented by subjectFIG. 2.

As shown by FIGS. 1B and 1C, the end terminations 30 and 32 of the FIG.1A arrangement provide connection to ground electrode internal geometryends 34 and 36, respectively, while the middle termination 38 providesconnection to signal electrode internal geometry top projection 40. Abottom termination (not shown in FIG. 1A) provides connection to signalelectrode internal geometry bottom projection 42.

The cross-sections of FIGS. 1B and 1C represent the vertical nature ofthe electrodes of the indicated exemplary embodiment relative to asupporting substrate or device or surface to which the embodiment willbe mounted. Such discrete vertical electrode filter generally 20 isintended in one use thereof for mounting in relation to an AIMD (activeimplantable medical device).

FIGS. 3A and 3B illustrate respective side and top views of conceptuallayouts of filter conductors 44, 46, and 48, positioned relative to arepresentative metal ferrule 50 and insulating feedthrough 52. Alsorepresented are wire conductors 54, 56, and 58 with which the discretefilters respectively associate.

As shown, such plurality of wire conductors 54, 56, and 58 (or pins insome instances) are supported through an insulating feedthrough 52,which is mounted relative to a metal ferrule 50. In practice, acorresponding plurality of the presently disclosed discrete verticalelectrode filters 44, 46, and 48 (filter capacitors) mount to the metalferrule for purposes of a ground connection and connect for input orsignal purposes to the corresponding plurality of feedthroughconductors, as illustrated. Representative filter 44 is shown in partialsee-through in both FIGS. 3A and 3B to illustrate the positioning of thevertical electrodes therein. As will be understood by those of ordinaryskill in the art, the representative filter outputs (top sideterminations) 60, 62, and 64 connect to internal circuitry of anassociated implantable medical device (not shown) while the bottom sideterminations thereof connect to their respective feedthrough conductors54, 56, and 58. As shown, respective end terminations of the filtercapacitors contact respective sides 66 and 68 of ferrule 50 for a groundconnection. For example, respective end terminations 70 and 72 of filtercapacitor 44 are electrically connected with members 66 and 68 offerrule 50.

FIGS. 4A and 4B and FIGS. 5A through 5C illustrate various alternativefeatures which may be used in conjunction with the presently disclosedsubject matter for optimizing performance of particular embodiments, allas selected by those of ordinary skill in the art devising particularembodiments for particular needs or applications.

Low cost assembly features may be obtained in part with asymmetricdimensions (in comparison with symmetric terminals) as shown by thecomparison between FIG. 4A (symmetric terminals) and FIG. 4B (asymmetricterminals). Representative filter 74 may have respective endterminations 76 and 78 on its dielectric body 80, which end terminationsare symmetrically positioned on such body 80. Also, a top sidetermination 82 may be matched by a bottom side termination (not seen inFIG. 4A). Representative filter 84 may have only one end termination 86to go along with its top side termination 88 (and a bottom sidetermination, not seen in FIG. 4B). As shown, such single end termination86 is asymmetrical with reference to dielectric body 90 of filter 84.Such asymmetric arrangements may provide ease of orientation, and mayprovide for improved high voltage performance. Also, the use of platedterminals may permit reflow soldering techniques and conductiveadhesives to be utilized. Further, the resulting structure (asrepresented by exemplary FIG. 4B) helps to keep ground features off thetop surface, when so desired.

Relatively lower series resistance features may be accommodated by thepresently disclosed subject matter, by incorporating a variety ofapproaches. As represented by FIGS. 5A, 5B, and 5C, such figuresillustrate respective approaches to lowering series resistance which maybe practiced in conjunction with the presently disclosed subject matter,particularly representing standard design, Low dcR design and LowdcR/ESR design, respectively. In essence, selected inner electrodes canbe repeated to reduce dcR and ESR. Also, low resistance metals may beused such as nickel, copper, or high purity silver. As will beunderstood from the representative illustrations of such FIGS. 5Athrough 5C, a representative body of dielectric material 92 may haveinterleaved sets of electrodes 94 and 96. In FIG. 5B (representativerelatively lower dcR design), electrodes 94 have been selectivelyrepeated. In FIG. 5C, (representative relatively lower dcR and ESRdesign), both sets of electrodes 94 and 96 have been selectivelyrepeated.

Further, presently disclosed subject matter may contribute to achievingrelatively higher breakdown voltage, through incorporation for exampleof fine-grained dielectrics, and/or low-stress electrode geometries.Specialty configurations may also be accommodated, such as the use oflow dielectric materials (for example, made from NPO dielectricmaterials) for RF connections, or involving short-circuited geometry toconnect a ground pin to an outer shield.

As represented by application FIGS. 6A and 6B, the presently disclosedmethodology for mounting the subject discrete feedthrough filter on aferrule/insulating feedthrough supporting surface uses surface tensionof solder for self-alignment of the device during reflow. In otherwords, the surface tension causes auto-rotation and centering of thepiece whenever the solder is heated up for reflow. Thereafter, aflex-circuit ribbon or nailhead lead (not shown) may be attached aftermounting, to secure the arrangement.

FIG. 6A is an exemplary embodiment of presently disclosed subjectmatter, similar to the illustrations of present application FIGS. 1A,3A, and 3B, and intended to be mounted on a ferrule and feedthrough astwo of such embodiments (of FIG. 6A) are represented in mountedconfiguration by the perspective illustration of present FIG. 6B. Thearrow 98 between FIGS. 6A and 6B show how an individual discrete device44 according to the presently disclosed subject matter is mounted on anexisting ferrule 50 and insulating feedthrough 52. In particular, theillustrated exemplary embodiment of FIG. 6A may have 0.126″ L×0.050″W×0.060″ H, a signal terminal ˜0.030″ sq, and a ground terminal 70 or 72˜0.030″ W having about 0.005″ wrap. Further, such exemplary capacitor 44embodiment may be built on CMAP with Ni electrodes and terminated withFCT (fine copper termination) plus NiSn or NiAu. Any thick-drop partswould require dummy electrode prints between active layers. Activelayers can be doubled to reduce ESR.

FIGS. 7A and 7B represent, respectively, side and end views of thesignal layer internal structures 100 for exemplary embodiment FIG. 6A,while FIG. 7C represents the ground layer internal structures 102 (sideview) of such exemplary embodiment. The end view FIG. 7B shows howsignal layers 100 may be alternately included within the dielectric 104of the filter capacitor.

FIG. 7C representative ground layer 102 may be one of an exemplaryembodiment which includes four active layers at 7.5 mil fired layerthickness. Per such embodiment, estimated capacitance using N370dielectric is 1,500 pF. Thinner layers would allow part height (i.e.,ESR) to be reduced.

FIG. 7D illustrates an alternative ground pattern 106 to that one shownby representative FIG. 7C. The result of such FIG. 7D alternative groundpattern is an asymmetric terminal configuration. As shown, that resultsin no wrapping of the termination on the top surface (generally 108) ofthe associated filter capacitor.

FIGS. 8A and 8B illustrate, respectively, end and top views (in partialsee-through illustration) of a discrete vertical feedthrough filter(generally 110) of presently disclosed subject matter in combinationwith a supporting ferrule 112, insulating feedthrough 114, and terminalwire 116, similar to the perspective view combination of subject FIG.6B. FIG. 8B illustrates the exemplary use of gold pads 118 on a Titaniumferrule element 112. FIG. 8C illustrates an enlarged top view inisolation of the presently disclosed discrete vertical feedthrough (FT)filter 110 otherwise shown in combination per the illustrations ofsubject FIGS. 8A and 8B. One example of an embodiment of such individualfilter element 110 per presently disclosed subject matter would be asize 1305 chip with 30 mil wide Sn-plated terminations. FIG. 8Brepresents a plurality of such filters received on ferrule 112 and eachrespectively associated with its own terminal wire or feedthroughconductor 116. One such filter 110 is omitted from the illustration ofFIG. 8B to better show the positioning of supporting pads 118 and one ofthe feedthrough conductors.

The two respective illustrations of subject FIG. 8D show top views ofrepresentative A and B patterns 120 and 122, respectively, for signalpins of the illustrated exemplary embodiment of present FIG. 8A. Theillustration of subject FIG. 8E shows a top view of a representativepattern 124 for RF pins as may be associated with the illustratedexemplary embodiment of present FIG. 8A. In some instances, specialtyconfigurations may also be accommodated, such as the use of lowdielectric materials (made from NPO dielectric materials) for therepresentative RF connections. The illustration of subject FIG. 8F showsa top view of a representative pattern 126 for ground pins as may beassociated with the illustrated exemplary embodiment of present FIG. 8A.

Beginning with a representative preliminary electrode layer design,present FIGS. 9A, 9B, and 9C, illustrate top views of respectivelysignal, ground, and dummy electrode layers 128, 130, and 132 of suchdesign. As noted by the arrow lines 134 and 136 at the bottom of theFIG. 9A illustration and at the left middle side of the FIG. 9Billustration, respectively, the indicated elements are added featuresfor a nucleate function occurring such as during an FCT (Fine CopperTermination, electroless plating) process. Alternatively, electrolyticplating or other plating may also be used in some embodiments.Similarly, the element 138 at the bottom of the FIG. 9C illustrationrepresents a dummy electrode which may be used to nucleate the FCTprocess.

Subject FIGS. 10A, 10B, and 10C respectively illustrate signal, ground,and dummy electrode layers 140, 142, and 144 as presently disclosed fora shielded design for increasing DWV (dielectric withstand voltage). Theshielding present in such layers will be understood by those of ordinaryskill in the art from comparing the respective layer illustrations fromFIGS. 9A through 9C to determine where there are added features(amounting to added shielding). For example, a comparison of therespective signal layers of FIGS. 9A and 10A shows additional protrudingshielding members 146 from the top and bottom FCT nucleation memberswhich otherwise appear at each vertical end of the signal layer 140.Similarly, comparison of the exemplary ground layers of respective FIGS.9B and 10B represent enlarged (shielded) areas 148 around each end ofthe central top-to-bottom extending feature of the ground layer 142.Also, such a comparison between the dummy layers 144 represented byexemplary FIGS. 9C and 10C shows similar additional protruding shieldingmembers 150 from the bottom and top FCT nucleation members 152 and 154,respectively in FIG. 10C relative to FIG. 9C, just as there were forFIG. 10A in comparison with FIG. 9A. Such added shielding features 150result in increased dielectric withstand voltage (DWV) characteristicsof the presently disclosed embodiments which incorporate such shieldingfeatures.

FIGS. 11A and 11B represent exemplary alternative device configurationswhich may be practiced in accordance with the presently disclosedsubject matter. FIG. 11A makes use of a symmetrical terminal filter 74similar to present FIG. 4A, while FIG. 11B makes use of an asymmetricalterminal filter 84 similar to present FIG. 4B. In particular, FIG. 11Arepresents a top view of a double-ended filter 74 as presently disclosedin association with a single row feedthrough 156 and associated ferrule158. As shown, end terminations 76 and 78 are associated with respectivelateral sides of ferrule 158. A top side termination 82 has a matchingbottom side termination (not seen in FIG. 11A) which connects with itsassociated feedthrough conductor 160. FIG. 11B represents a top view ofa single-ended filter 84 as presently disclosed in association with adouble row feedthrough 164 and associated ferrule 166. The end terminal86 of single-ended filter 84 is associated with one lateral side offerrule 166, while a bottom side termination (not seen) opposite the topside termination 162 of filter 84 is associated with a respective one offeedthrough conductors 162. Another conductor 162′ in the other line ofdouble row feedthrough 164 is associated with a bottom side termination(not seen) of single-ended filter 84′ which is opposite top sidetermination 88′ thereof. As shown, the asymmetrical filters 84 and 84′may be used in alternately opposite positions, to respectively cover therespective rows of conductors of the dual row feedthrough 164. Thepositions of the conductors 162 and 162′ illustrated with filters 84 and84′, respectively, are shown with dotted lines, since they otherwise inthe top view of FIG. 11B are not visible below their respective filters.

Those of ordinary skill in the art will appreciate from the completedisclosure herewith various potential benefits from various presentlydisclosed embodiments. For example, in many instances, lowermanufacturing costs may occur. Also, since discrete devices arecontemplated, each device is not tied down to a specific associatedcomponent pitch. That makes the individual devices more universal intheir potential applications. Additionally, with such improveduniversality of the feedthrough filters, that improves the ability forconcurrent development of modifications of feedthrough structures forother facets or purposes of technology. Further, due to their discretenature as associated with the various plurality of lead wires or pins(see, for example, FIGS. 3A, 6B, and 8B), there is substantial reductionin any cross-talk behavior between adjacent and/or nearby signal lines.Similarly, owing to their discrete nature, there is the opportunity fornew development of interconnection schemes, for example, such asflex-circuit connections.

While the presently disclosed subject matter has been described indetail with respect to specific embodiments thereof, it will beappreciated that those skilled in the art, upon attaining anunderstanding of the foregoing may readily adapt the presently disclosedtechnology for alterations or additions to, variations of, and/orequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations, and/or additions to the presently disclosedsubject matter as would be readily apparent to one of ordinary skill inthe art.

What is claimed is:
 1. A feedthrough filter arrangement for use with anAIMD, comprising: a ferrule; a feedthrough associated with said ferrule;a plurality of conductors supported through said feedthrough; and acorresponding plurality of discrete filters, each of said filters havingat least two respective terminals, with one of said terminals associatedwith a respective one of said conductors, and the other of saidterminals associated with said ferrule.
 2. A feedthrough filterarrangement as in claim 1, wherein said conductors comprise respectivewire conductors for each of said discrete filters.
 3. A feedthroughfilter arrangement as in claim 1, wherein: said ferrule comprises ametal ferrule; and said feedthrough comprises an insulating cofiredfeedthrough which is mounted relative to said metal ferrule.
 4. Afeedthrough filter arrangement as in claim 1, wherein: each of saidfilters has side and end terminals, and has two sets of interleavedvertical electrodes comprising ground electrodes and signal electrodes;each of said ground electrodes has respective projecting end portionsconnecting with respective end terminals of each of said filters; andeach of said signal electrodes has respective projecting side portionsconnecting with respective side terminals of each of said filters.
 5. Afeedthrough filter arrangement as in claim 1, wherein: said at least tworespective terminals comprise side and end terminals associatedrespectively with said filters and said ferrule; and each of saidfilters has two sets of interleaved vertical electrodes comprisingground electrodes and signal electrodes, wherein said ground electrodesare associated with at least one end terminal of each respective filterso that ground is connected to said ferrule, and wherein said signalelectrodes are associated with at least one side terminal of eachrespective filter so that signals on a respective associated conductorare connected to such associated conductor.
 6. A feedthrough filterarrangement as in claim 5, wherein said respective side and endterminals comprise asymmetrical terminals.
 7. A feedthrough filterarrangement as in claim 6, wherein said feedthrough includes a doublerow of conductors supported therethrough, and wherein said filters aremounted on said feedthrough in a row with end terminals thereof onalternate sides of said feedthrough.
 8. A feedthrough filter arrangementas in claim 5, wherein side terminals of said filters compriserespective top and bottom side terminals, with each bottom side terminalrespectively connected to the associated conductor of its filter, andwith each top side terminal connected to an associated AIMD.
 9. Afeedthrough filter arrangement as in claim 5, wherein said respectiveside and end terminals include at least a pair of end terminals for eachrespective filter, and comprise symmetrical terminals for eachrespective filter.
 10. A feedthrough filter arrangement as in claim 9,wherein: said ferrule comprises a titanium ferrule with sets of uppersurface gold pads attached to ground of said ferrule; and said filtersare mounted relative to said ferrule such that said end terminals foreach respective filter are attached to a set of said gold pads of saidferrule.
 11. A feedthrough filter arrangement as in claim 9, whereinsaid conductors are supported in a single row in said feedthrough, andrespective end terminals of each of said filters are mounted on oppositesides of said feedthrough, with a bottom side terminal of each of saidelements situated over respective of said conductors.
 12. A feedthroughfilter arrangement as in claim 5, wherein at least some of said filtersfurther include additional ground electrodes for relatively lower dcRfilter characteristics.
 13. A feedthrough filter arrangement as in claim5, wherein at least some of said filters further include additionalsignal electrodes for relatively lower ESR filter characteristics.
 14. Afeedthrough filter arrangement as in claim 5, wherein at least some ofsaid filters further include: additional ground electrodes forrelatively lower dcR filter characteristics; and additional signalelectrodes for relatively lower ESR filter characteristics; and whereinsaid electrodes comprise relatively lower resistance metals.
 15. Afeedthrough filter arrangement as in claim 5, wherein said filtersinclude relatively low dielectric materials made from NPO dielectricmaterials.
 16. A feedthrough filter arrangement as in claim 5, whereinsaid filters further include a plurality of dummy electrode layersproviding nucleation areas for plating formation of filter terminals.17. A feedthrough filter arrangement as in claim 16, wherein said groundand signal electrodes and said dummy electrode layers include additionalshielding members for relatively increasing the dielectric withstandingvoltage characteristics of said filters.
 18. A feedthrough filterarrangement for use in association with external circuitry, comprising:a metal ferrule; an insulating feedthrough associated with said ferrule;a plurality of wire conductors supported through said feedthrough; and acorresponding plurality of discrete cofired filter capacitors, each ofsaid filter capacitors having: respective end terminals; a top sideterminal; a bottom side terminal; a body of dielectric material; and twosets of interleaved vertical electrodes comprising ground electrodes andsignal electrodes received in said body of dielectric material, whereineach of said ground electrodes has respective projecting end portionsconnecting with respective end terminals of each of said filtercapacitors, and each of said signal electrodes has respective projectingside portions connecting with respective side terminals of each of saidfilter capacitors; wherein respective end terminals of each of saidfilter capacitors are mounted on opposite sides of said ferrule for aground connection therewith, and with a bottom side terminal of each ofsaid filter capacitors connected with a respective one of saidconductors for a signal connection therewith, so that each of said topside terminals of said filter capacitors are exposed for respectiveconnections with associated external circuitry.
 19. A feedthrough filterarrangement as in claim 18, wherein at least some of said filtercapacitors further include: additional ground electrodes for relativelylower dcR filter capacitor characteristics; and additional signalelectrodes for relatively lower ESR filter capacitor characteristics.20. A feedthrough filter arrangement as in claim 18, wherein: saidferrule comprises a titanium ferrule with sets of upper surface goldpads attached to ground of said ferrule; and said filter capacitors aremounted relative to said ferrule such that said end terminals for eachrespective filter are attached to a set of said gold pads of saidferrule.
 21. A feedthrough filter arrangement as in claim 18, wherein atleast some of said filter capacitors further include a plurality ofdummy electrode layers providing nucleation areas for plating formationof filter capacitor terminals.
 22. A feedthrough filter arrangement asin claim 21, wherein said ground and signal electrodes and said dummyelectrode layers include additional shielding members for relativelyincreasing the dielectric withstanding voltage characteristics of saidfilter capacitors.
 23. Methodology for a feedthrough filter arrangementfor use with an active implanted medical device (AIMD), comprising:providing a metal ferrule; fitting an insulating feedthrough with saidferrule; supporting a plurality of conductors through said feedthrough;and connecting respectively a corresponding plurality of discretecofired filters with said plurality of conductors, so as to reducecross-talk between signals on adjacent of said conductors. 24.Methodology as in claim 23, further including: providing a double row ofconductors supported through said feedthrough; and providing each ofsaid filters with at least one end terminal and at least one sideterminal; and mounting said filters on said feedthrough in a row withend terminals thereof on alternate sides of said feedthrough. 25.Methodology as in claim 23, further including connecting and directlymounting said plurality of discrete cofired filters with a printedcircuit board instead of connecting with said plurality of ferruleconductors.
 26. Methodology as in claim 23, further including providingeach of said filters with at least two respective terminals, with one ofsaid terminals associated with a respective one of said conductors, andthe other of said terminals associated with said ferrule. 27.Methodology as in claim 26, further including providing said filterterminals as either symmetrical or asymmetrical terminals. 28.Methodology as in claim 26, wherein: said at least two respectiveterminals comprise side and end terminals associated respectively withsaid filters and said ferrule; and each of said filters has two sets ofinterleaved vertical electrodes comprising ground electrodes and signalelectrodes, wherein said ground electrodes are associated with at leastone end terminal of each respective filter so that ground is connectedto said ferrule, and wherein said signal electrodes are associated withat least one side terminal of each respective filter so that signals ona respective associated conductor are connected to such associatedconductor.
 29. Methodology as in claim 28, wherein side terminals ofsaid filters comprise respective top and bottom side terminals, witheach bottom side terminal respectively connected to the associatedconductor of its filter, and with each top side terminal connected to anassociated AIMD.
 30. Methodology as in claim 23, wherein each of saidfilters comprise filter capacitors having respective end terminals, atop side terminal, a bottom side terminal, a body of dielectricmaterial; and two sets of interleaved vertical electrodes comprisingground electrodes and signal electrodes received in said body ofdielectric material, wherein each of said ground electrodes hasrespective projecting end portions connecting with respective endterminals of each of said filter capacitors, and each of said signalelectrodes has respective projecting side portions connecting withrespective side terminals of each of said filter capacitors. 31.Methodology as in claim 30, further including selectively providingadditional electrodes to said filter capacitors for relatively lower dcRand/or relatively lower ESR filter characteristics.
 32. Methodology asin claim 30, further including selectively providing a plurality ofdummy electrode layers to said filter capacitors for providingnucleation areas for plating formation of filter capacitor terminals.33. Methodology as in claim 32, further including selectively providingadditional shielding members to selected of said ground and signalelectrodes and said dummy electrode layers for relatively increasing thedielectric withstanding voltage characteristics of said filtercapacitors.
 34. Methodology as in claim 30, wherein respective endterminals of each of said filter capacitors are mounted on oppositesides of said ferrule for a ground connection therewith, and with abottom side terminal of each of said filter capacitors connected with arespective one of said conductors for a signal connection therewith, sothat each of said top side terminals of said filter capacitors areexposed for respective connections with associated external circuitry.35. Methodology as in claim 34, wherein mounting of said end terminalsof said filter capacitors on said ferrule includes using surface tensionof solder for self-alignment of said capacitors during a solder reflowstep, which causes auto-rotation and centering of the capacitor wheneverthe solder is heated up for reflow.
 36. Methodology as in claim 35,further including attaching a lead to said capacitor after said reflowstep, to secure the positioning of said capacitor relative to saidferrule.